Some books aren’t meant for the movies. When the union is forced, it can cause an allergic reaction in the viewer, who may slump in his or her seat, wondering uneasily whether to ask if there’s a dermatologist in the house (e.g., “The World According to Garp”).

Renee Zellweger in “Bridget Jones’s Diary”

On the other hand, some works from the literary world gag for onscreen treatment, just gag for it. “Bridget Jones’s Diary” is one of them.

Containing some of the best dialogue to appear between the covers of a paperback in the last decade and with real and lovable characters wading through real and lovable problems (calculating how many seconds have passed since they last had sex), it was almost impossible to devour without mentally construing a soundtrack for it at the same time. Something with Eric Carmen’s “All By Myself” in it, perhaps . . .

And now it turns out that the soundtrack s have “All By Myself” in it. Hah, triumph! Perhaps better to just quit job and offer services to posh Brit production company as soundtrack imaginer or equivalent. Ummmmm.

Ah . . . Excuse me for launching into Bridget-speak. But such is the effect of “Bridget Jones’s Diary,” which was written by Londoner Helen Fielding some five years ago and became a torrential global bestseller.

I’m sure I’m not the only female who secretly calculated daily weight gains and alcohol consumption levels and compared them with Bridget’s (hers were written at the head of each entry), then greeted the results with a huge sigh of relief (“Yessssss!”) or a groan (“Oh, nooooooo!”). I’m also sure I’m not the only female who compared her own lying, scheming, uncaring boyfriend to Bridget’s love object Daniel and took comfort in the proof that all men, even fictitious ones, are bastards.

Anyway, back to the movie. Because I’m heavily biased when it comes to “Bridget,” it’s difficult to come up with insightful and objective opinions; but even so, I must state that as screen adaptations go, this one is a winner.

And the reason rests primarily with Renee Zellweger in the title role. Formerly known as Tom Cruise’s girlfriend in “Jerry Maguire” and Jim Carrey’s ex in real-life, Zellweger shows the world what she’s made of by putting on 10 kg, wearing red pajamas patterned with penguins and eating Nutella straight from the jar.

She’s also sporting enough to reveal her “scary pants” — a large beige corset designed to hold everything in, in a manner that defies the law of gravity, thereby achieving the desired look of slimness/slinkiness in a little black evening dress. Ten years ago, the only Hollywood thespian willing to stock up on body fat was Robert De Niro. And now Zellweger has done the same — with no prosthetic clothing or digital effects. Just for this, you want to jump into the screen and cuddle her on her terrible sofa in her cluttered London flat.

Directed by Sharon Maguire (an award-winning BBC documentary-maker and friend of Fielding, who also happens to be the model for one of Bridget’s best friends, Shaz), this is a picture that gets right down to the brass tacks of singleton urban living for women in their 30s. Bridget’s dilemma is achingly familiar: Her concerns about her career, becoming a better person and losing weight, inevitably cave into concerns about finding a “functional boyfriend” and gaining the equilibrium needed to concentrate on said career, becoming a better person, losing weight, etc.

Each New Year’s party at her parents’ house depresses Bridget with the realization that, once again, she has shown up sans date, and once again, her mother will try to fix her up with some depressing barrister (Colin Firth), wearing a sweater with a reindeer on the front. Each year that passes brings news of some friend or other escaping the world of “singletons” for the camp of “smug marrieds.”

But fate, or rather her roguish yet irresistible boss Daniel Cleaver (played excellently by Hugh Grant), smiles upon Bridget. After a frantic exchange of flirtatious office e-mail, he takes her out and a semi-relationship develops that involves a weekend in the country. Bridget is thrilled: “A minibreak proves this isn’t just sex, it’s true love!” But alas, her euphoria is smashed to smithereens when Daniel ditches her for a tall, tanned, not-yet-30 American, who takes one disdainful look at Bridget and says: “I thought you said she was thin.” Owwwwch.

In the grand tradition of screen adaptations, the story sprints past Bridget’s misery and rushes headlong to the preordained happy ending, but this won’t irritate you at all. In fact, you’ll insist that she get her proper dose of joy as quickly as possible, because by this time you will be deeply in love with Bridget/Zellweger.

Rumor has it that Zellweger turned down the offer of a sequel, as she didn’t want to go though the process of gaining and shedding weight again. So this could be our last opportunity to see her scrutinize her underwear while smoking/gorging tiramisu. I wager, however, that this won’t be the last time we see Zellweger in an English production sporting a very posh accent. Watch out, Gwyneth Paltrow.